thanks for helping me eol! I tried what you asked me to but still i cant find the .png file in the hdr folder. inside the hdr folder i find another folder named after the date and time but its empty. the following is the exact output i get on the console:

/bracketing $ ./bracket-manual.sh
sleeping for 5 seconds..
presets: 2462 17897 33333
acquiring: 2462
snapping image at 2462, requested: 2462
WARNING: erroneous pipeline: no element "pngenc"
saved to /home/user/MyDocs/hdr/20100417121852/raw-02462.png
acquiring: 17897
snapping image at 17917, requested: 17897
WARNING: erroneous pipeline: no element "pngenc"
saved to /home/user/MyDocs/hdr/20100417121852/raw-17917.png
acquiring: 33333
snapping image at 33333, requested: 33333
WARNING: erroneous pipeline: no element "pngenc"
saved to /home/user/MyDocs/hdr/20100417121852/raw-33333.png
images stored in /home/user/MyDocs/hdr/20100417121852/
DONE! Yay!

I looked into 20100417121852 folder but its empty